Using an ext2 file system on a flash memory card
(like CompactFlash, SD, MMC or a USB memory stick)
is standard technology.
To avoid unnecessary flash wear it is a good idea to mount
the root file system read-only,
or at least using the "noatime" mount option.

For our test we can use the "ext2.img" file from the previous
step without changes:

In this test we use a standard CompactFlash card
which comes with a single partition on it. We use U-Boot to copy
the ext2 file system image into this partition:

Note that the "ide write" command takes parameters as hex numbers,
and the write count is in terms of disk blocks of 512 bytes each.
So we have to use 0x20 for the starts sector of the first partition,
and 3788800 / 512 = 7400 = 0x1CE8 for the block count.

We now prepare the Linux boot arguments
to take this partition as read-only root device: